Fermion-Boson Stars in Scalar-Tensor Gravity
Abstract
In the massless Damour-Esposito-Farèse scalar-tensor theory of gravity, we numerically construct static, spherically symmetric star models composed of a mixture of fermionic and bosonic matter, interacting purely gravitationally. The fermionic sector is modeled as a perfect fluid, while the bosonic sector is described by a massive, free, complex scalar field. We demonstrate that mixed fermion-boson stars can undergo spontaneous scalarization, and we systematically investigate the role played by the bosonic field across different regimes of bosonic mass, central fermionic pressure, and central bosonic amplitude. Our analysis reveals a complex interplay among the parameters, giving rise to a variety of scalarized configurations, ranging from fermionic matter embedded within extended bosonic halos to bosonic cores confined within fermionic matter. We examine sequences of solutions, in particular mass-radius surfaces, and we determine the critical coupling parameter for the onset of scalarization.
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BibTeX
@misc{mourelle2026fermionboson,
title = {{Fermion-Boson Stars in Scalar-Tensor Gravity}},
author = {Jorge Castelo Mourelle and Saeed Fakhry and Néstor Ortiz},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38747},
eprint = {2610.38747},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38747},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Fermion-Boson Stars in Scalar-Tensor Gravity
AU - Jorge Castelo Mourelle
AU - Saeed Fakhry
AU - Néstor Ortiz
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38747
UR - https://arxiv.org/abs/2610.38747
AB - In the massless Damour-Esposito-Farèse scalar-tensor theory of gravity, we numerically construct static, spherically symmetric star models composed of a mixture of fermionic and bosonic matter, interacting purely gravitationally. The fermionic sector is modeled as a perfect fluid, while the bosonic sector is described by a massive, free, complex scalar field. We demonstrate that mixed fermion-boson stars can undergo spontaneous scalarization, and we systematically investigate the role played by the bosonic field across different regimes of bosonic mass, central fermionic pressure, and central bosonic amplitude. Our analysis reveals a complex interplay among the parameters, giving rise to a variety of scalarized configurations, ranging from fermionic matter embedded within extended bosonic halos to bosonic cores confined within fermionic matter. We examine sequences of solutions, in particular mass-radius surfaces, and we determine the critical coupling parameter for the onset of scalarization.
ER -